Limited strain wrench



C. L. COX

LIMITED STRAIN WRENCH Filed July 27, 1956 ATTORNEY iNVENTOR GENO/YD L. Cox

Patented Oct. 5, 1937 UNITED STATES 2,094,584 PATENT OFFICE 2,094,584 LIMITED STRAIN WRENCH Ormond L. Cox, United States Navy Application July 27, 1936, Serial No. 92,703

1 Claim.

(Granted under the act of March amended April 30, 1928 370 O.

This invention relates to a limited strain wrench, and has for an object to provide an improved wrench that will exert only a predetermin'ed amount of strain on'the nut on which it is to be used and that will become inoperative when the nut'has been tightened to the predetermined amount or a limited strain has been reached.

A further object of this invention is to provide a limited-strain wrench utilizing a shearing pin, which is selected according to thelimit of strain that is desired for the particular purpose.

The wrench of this invention may be used for tightening nuts when securing cylinder heads of steam or internal combustion engines to insure that the nuts are all tightened to the .same degree. A further use is for tightening nuts on bolts or studs in making up pipe joints orin tightening the glands of .stufling boxes, or in per- 2 mitting the use of studs or bolts of smaller diameter than now customarily used in many cases where larger sized bolts or nuts are used solely to withstand a sever tightening. A particular intended use of this invention is in installing 25 boiler gauge glasses where it is obvious that too much pressure on the mounting bolts would crack the glass gauge, whil would permit the same' 'to leak.

With the foregoing and other objects in view, 80 the invention consists in the construction, combination and arrangement described-more fully hereafter.

In the drawing:

Fig. 1 is aperspective view of the assembled 35 wrench, ready for use;

Fig. 2 is a sectional view of the wrench handle; Fig. 3 is a partly sectional view of the socket of this wrench, and Fig. 4 is a plan view of a wire nail used as a 40 shearing pin.

There is shown at! thelimited strain wrench of this invention, which includes a socket ll having a hexagonal opening 12 therein of a proper size to fit over the nut to be tightened.

45 Extending from the top of the socket H is a circular boss l3 from the a threaded pin l4 adapted to receive a nut l5 and a washer l6. Extending from the top of the socket l2 and at one side thereof is a leg l1 60 having an aperture l8 extending therethrough,

the aperture It! being of shearing pin, as shown at A wrench handle is provided at one end;

with a circular opening 2| of a diameter to lit 85 somewhat loosely about the circular boss I 3. The thickness of the handle 20 is slightly less than the height of the circular boss l3 and a e too little pressure of parts as'will be center of which extends a size to receive the a, 1883, as G. 75'!) perforation 22 corresponding in size to the perforation l8 and shearing pin l9 extends through the handle 20 at the same distance from the center of the circular aperture 2| as is the perf'oration l8 from the center of the socket wrench In operation, the handle 20 is placed over the circular boss l3 and rotatabiy held thereon by means of the nut l5 and washer l6 placed on the threaded pin l4 extending from the center of the top of the socket wrench II. The leg 11 may then be rotated so as to bring the aperture l8 into alignment with the aperture 22, whereupon the shearing pin I9 is placed through the aligned apertures 22 and Ill. The socket opening I2 is then placed over the nut to be tightened and the handle 20 rotated with a steady pull, tightening the nut until the shearing strength of the pin I9 is exceeded, whereupon the pin i9 will shear, releasing the strain on the nut within the socket l2 and permitting the'handle' to pivot on the boss l3, with no further turning effect of the wrench ll.

In order to tighten another nut the leg l1 and the handle 20 are again rotated relative to each other to bring the pin apertures into alignment, and a new shearing pin is placed therethrough, making it ready for further operation.

Other modifications and changes in the proportions and arrangements of the parts may be made by those skilled in the art without departing from the nature and scope of the invention, as defined in the appended claims.

The invention described herein may be manufactured and used by or for the Government of. the United States of America for governmental purposes, without the paym nt of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

A limited-strain wrench, comprising a wrench socket, a leg extending from the top of said socket toward one side thereof, a circular boss extending from the center of the back of said socket a handle, said handle having a circular aperture near one end thereof, means for rotatably securing said handle on said circular boss, and shearing means providing the sole preventive to relative rotation of said handle to said wrench socket until the strength of saidshearing means is exceeded, said shearing means comprising a shearing pin placed through aligned apertures in said handle and said extending leg of said wrench socket, whereby when said pin is sheared said handle may rotate freely relative to said 55 

